Question Converting sound bar to center channel

mpfjr

Novice Member
I have an LG SJ8 sound bar on the bottom of my LG TV. The problem with this soundbar is that it can't get the audio synced with the video. I tried a different brand of sound bar and there are no issues with it. So I am reasonably sure the sound bar is the problem.

On top of that I want ATMOS which this sound bar can't do. So I bought a Yamaha 683 AVR and now I am shopping for speakers.

What occurred to me was using the shell of the sound bar with its existing speakers as a center channel since it fits so nice under my TV and looks classy. Also the sound was pretty good I thought.

So I took it apart and measured the resistance of each speaker.

The sound bar is split right and left with speaker "modules" on each extreme end. Which is great!

On the furthest outside there is a .75" tweeter that is 6 ohms. I disconnected it and measured with my digital multi meter at 5.3 ohms of resistance. So I am assuming that it is a 6 ohm speaker. Then there are two rectangle speakers that are wired in parallel. Each speaker is 8ohm on its own but 4 ohm at the plug.

The tweeter is a seperate set of wires. So I find this interesting that they would mix 6ohm tweeters with 8/4 ohm drivers.

So the way I see it I have 6 speakers to deal with and a center channel would have only one channel. So all 6 speakers would operate as one.

This is where my understanding falls apart. I don't know where to go next.

How do I wire these up?
So the native orientation in ohms is( 6, 8, 8), (8, 8, 6) where current wiring configuration is (6,4), (4,6).

I was just looking at this site: How to hook up speakers correctly for proper impedance and there seems to be some good information there as well as a formula that may help. Now I just need to understand it.

From what I understand from that formula I have .125 x 4 and .166 x 2 = .5 + .33 = .83 which I have to divide into 1 which is 1.20 ohms. Which of course is too far from where I need to be.

Also would I need a crossover?
 
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felix991

Novice Member
I take it no one ever answered you on this? Because I had the same want. I have a really nice Onkyo SoundBar that fits perfect and matches the rest of the eq and I too took mine apart and got about the same measurements, the only conclusion I could come up with was create my own crossover and run it off the power amp from the receiver by-passing all the internal circuitry.

I really like this sound bar instead of some others I have tried because it very clear on the voices and I can hear the dialog better than others. (I have a living room and a movie room) but it's really a size thing. I can not fit any other speaker setup in my current cabinet.

If I try to use the soundbar in conjunction with the 7.1 stereo even feeding the signal off the output of the receiver to the SB, I get a terrible delay between the two amps that will not stay in sync no matter what I try and set. So the answer was as you posted.

If you ever came up with any ideas, please let me know.
 

sarnovian

Standard Member
I know this is a very late response and I'm sure you moved on. However, I was looking for similar information myself as I wanted to convert my Martin Logan Vision soundbar into a center channel as it is quite a good speaker (3x folded ribbon tweeters, and 4x midbass drivers) but there is no easy way to make it work in its original configuration as part of a full surround system. So to help other people who might be interested in the same type of project I decided to post this info.

Essentially you have to add a passive 2 or 3 way crossover into your soundbar and remove all the built in amps/digital stuff. You need to wire your drivers into series, parralel or a combo thereof to create 4-8ohm loads for the crossover and to make your external AVR/Amps happy. In the case of the Martin Logan Vision it has 4x 4Ohm midbass drivers, and 3x 6Ohm tweeters. I chose to wire the 4x mids in two sets of series (4x Ohm *2 series == 8Ohms) then put the two pairs in parallel for a 4 Ohm equivalent load. The tweeters I wired the outer two in series for 12ohms, then paralleled this with the center tweeter for a equivalent 4ohm load. The tweeters are connected to the high pass output of the passive crossover (2.3-3.6Khz and above) and the mids to the low pass. I'll use the AVR externally to put a low pass of 60-100Hz on the center channel after I tune the system. NOTE since the tweeters are not even pairs, more energy (watts) will go to the center tweeter than the outer ones, but that should be ok (hopefully!)

See the diagram for details. You can use this concept for most multi-speaker soundbar conversions.

Once I get DIRAC Live setup soon I'll post some EQ charts to show how well or how
 

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puneet83

Active Member
This sounds like a good project for someone with a spare soundbar.
I know people put emphasis on timbre matching and keeping the LCR same etc., but sometimes it pays to experiment.
Knowing how loud some of these bars can go, I imagine the manufacturers use some efficient drivers which should be easy to drive and work well for dialogues and vocals.
Good luck and let us know what you think of end result.
 

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